/*
 Copyright  2005 MySQL AB, 2008 Sun Microsystems
 All rights reserved. Use is subject to license terms.

  The MySQL Connector/J is licensed under the terms of the GPL,
  like most MySQL Connectors. There are special exceptions to the
  terms and conditions of the GPL as it is applied to this software,
  see the FLOSS License Exception available on mysql.com.

  This program is free software; you can redistribute it and/or
  modify it under the terms of the GNU General Public License as
  published by the Free Software Foundation; version 2 of the
  License.

  This program is distributed in the hope that it will be useful,  
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
  02110-1301 USA

 */

package com.mysql.jdbc;

import java.sql.ParameterMetaData;
import java.sql.SQLException;
import java.sql.Types;

public class MysqlParameterMetadata implements ParameterMetaData {
	boolean returnSimpleMetadata = false;

	ResultSetMetaData metadata = null;

	int parameterCount = 0;

	private ExceptionInterceptor exceptionInterceptor;
	
	MysqlParameterMetadata(Field[] fieldInfo, int parameterCount, ExceptionInterceptor exceptionInterceptor) {
		this.metadata = new ResultSetMetaData(fieldInfo, false, exceptionInterceptor);

		this.parameterCount = parameterCount;
		this.exceptionInterceptor = exceptionInterceptor;
	}

	/**
	 * Used for "fake" basic metadata for client-side prepared statements when
	 * we don't know the parameter types.
	 * 
	 * @param parameterCount
	 */
	MysqlParameterMetadata(int count) {
		this.parameterCount = count;
		this.returnSimpleMetadata = true;
	}

	public int getParameterCount() throws SQLException {
		return this.parameterCount;
	}

	public int isNullable(int arg0) throws SQLException {
		checkAvailable();

		return this.metadata.isNullable(arg0);
	}

	private void checkAvailable() throws SQLException {
		if (this.metadata == null || this.metadata.fields == null) {
			throw SQLError.createSQLException(
					"Parameter metadata not available for the given statement",
					SQLError.SQL_STATE_DRIVER_NOT_CAPABLE, this.exceptionInterceptor);
		}
	}

	public boolean isSigned(int arg0) throws SQLException {
		if (this.returnSimpleMetadata) {
			checkBounds(arg0);

			return false;
		}

		checkAvailable();

		return (this.metadata.isSigned(arg0));
	}

	public int getPrecision(int arg0) throws SQLException {
		if (this.returnSimpleMetadata) {
			checkBounds(arg0);

			return 0;
		}

		checkAvailable();

		return (this.metadata.getPrecision(arg0));
	}

	public int getScale(int arg0) throws SQLException {
		if (this.returnSimpleMetadata) {
			checkBounds(arg0);

			return 0;
		}

		checkAvailable();

		return (this.metadata.getScale(arg0));
	}

	public int getParameterType(int arg0) throws SQLException {
		if (this.returnSimpleMetadata) {
			checkBounds(arg0);

			return Types.VARCHAR;
		}

		checkAvailable();

		return (this.metadata.getColumnType(arg0));
	}

	public String getParameterTypeName(int arg0) throws SQLException {
		if (this.returnSimpleMetadata) {
			checkBounds(arg0);

			return "VARCHAR";
		}

		checkAvailable();

		return (this.metadata.getColumnTypeName(arg0));
	}

	public String getParameterClassName(int arg0) throws SQLException {
		if (this.returnSimpleMetadata) {
			checkBounds(arg0);

			return "java.lang.String";
		}

		checkAvailable();

		return (this.metadata.getColumnClassName(arg0));
	}

	//只支持in模式，因为这个类只是针对java.sql.PreparedStatement
	//java.sql.CallableStatement对应的是:
	//com.mysql.jdbc.CallableStatement.CallableStatementParamInfo
	public int getParameterMode(int arg0) throws SQLException {
		return parameterModeIn;
	}

	private void checkBounds(int paramNumber) throws SQLException {
		if (paramNumber < 1) {
			throw SQLError.createSQLException("Parameter index of '"
					+ paramNumber + "' is invalid.",
					SQLError.SQL_STATE_ILLEGAL_ARGUMENT, this.exceptionInterceptor);
		}

		if (paramNumber > this.parameterCount) {
			throw SQLError.createSQLException("Parameter index of '"
					+ paramNumber
					+ "' is greater than number of parameters, which is '"
					+ this.parameterCount + "'.",
					SQLError.SQL_STATE_ILLEGAL_ARGUMENT, this.exceptionInterceptor);

		}
	}
	
	/**
     * Returns true if this either implements the interface argument or is directly or indirectly a wrapper
     * for an object that does. Returns false otherwise. If this implements the interface then return true,
     * else if this is a wrapper then return the result of recursively calling <code>isWrapperFor</code> on the wrapped
     * object. If this does not implement the interface and is not a wrapper, return false.
     * This method should be implemented as a low-cost operation compared to <code>unwrap</code> so that
     * callers can use this method to avoid expensive <code>unwrap</code> calls that may fail. If this method
     * returns true then calling <code>unwrap</code> with the same argument should succeed.
     *
     * @param interfaces a Class defining an interface.
     * @return true if this implements the interface or directly or indirectly wraps an object that does.
     * @throws java.sql.SQLException  if an error occurs while determining whether this is a wrapper
     * for an object with the given interface.
     * @since 1.6
     */
	public boolean isWrapperFor(Class iface) throws SQLException {

		// This works for classes that aren't actually wrapping
		// anything
		return iface.isInstance(this);
	}

    /**
     * Returns an object that implements the given interface to allow access to non-standard methods,
     * or standard methods not exposed by the proxy.
     * The result may be either the object found to implement the interface or a proxy for that object.
     * If the receiver implements the interface then that is the object. If the receiver is a wrapper
     * and the wrapped object implements the interface then that is the object. Otherwise the object is
     *  the result of calling <code>unwrap</code> recursively on the wrapped object. If the receiver is not a
     * wrapper and does not implement the interface, then an <code>SQLException</code> is thrown.
     *
     * @param iface A Class defining an interface that the result must implement.
     * @return an object that implements the interface. May be a proxy for the actual implementing object.
     * @throws java.sql.SQLException If no object found that implements the interface 
     * @since 1.6
     */
	public Object unwrap(Class iface) throws java.sql.SQLException {
    	try {
    		// This works for classes that aren't actually wrapping
    		// anything
    		return Util.cast(iface, this);
        } catch (ClassCastException cce) {
            throw SQLError.createSQLException("Unable to unwrap to " + iface.toString(), 
            		SQLError.SQL_STATE_ILLEGAL_ARGUMENT, this.exceptionInterceptor);
        }
    }
}
